The greatest risk factor for nearly all neurodegenerative diseases is aging, yet, the molecular identity of the age associated mechanisms are not known. The central hypothesis of this proposal is that continual production of aggregation prone proteins eventually leads to age onset proteotoxicity and disease. The key question to address is what are the molecular mechanisms that prevent proteotoxicity during early life that become compromised with age. To address this question, in the first part of our work,we will expand upon our results in C. elegans that point towards a protective disaggregation activity and the formation of larger, less toxic high molecular weight aggregates that are regulated by the insulin/IGF-1 pathway. From our preliminary results it is clear that a distinct biochemical activity encoded by the HSF-1 transcriptome is partially responsible for the protective dissaggregation activity. However, it is not clear if there is a distinct active aggregation activity encoded by the DAF-16 transcriptome to create large, less toxic, A(3structures. Alternatively, the DAF-16 transcriptome may regulate the expression of factors critical for a cellular event, such as endocytic movement of A(3toxic structures that results in large aggregates forming from smaller toxic structures. To identify and characterize the components of these activities, we will employ bioinformatic, genetic and proteomic analysis to complement the biochemical approaches of the Kelly lab and the cell biological analysis of the Balch lab.In the next part of our work, in collaboration with the Masliah lab, we will evaluate whether the same protective mechanisms exists in mammals. In the third specific aim, using biophysical data generated in the Riek lab, we will create transgenic worms that express structurally trapped isoforms of A(31-42. Genetic modifiers of proteotoxicityfrom the worm-based models will be further explored in murine models by the Masliah lab using lentivirus technology. Finally, our preliminary results indicate that insulin/IGF-1 signaling is not the only aging regulatory pathway that can protect animals from Apl-42 mediated toxicity. We will broaden the scope of our research to understand how reduced mitochondrial function and diet restriction can delay age onset proteotoxicity and their potential mechanism.